Slow-release fertilizer spike having high crush-resistance

ABSTRACT

A slow-release fertilizer composition, having a crushing strength in excess of 2,000 p.s.i., comprises a water-soluble urea-formaldehyde resin, a granular filler material and a binder derived from magnesia and phosphoric acid. The composition is prepared as a paste and extruded in the form of a beveled spike.

United States Patent [72] Inventor: Henry C. Messman, Mamaroneck, NY.

[73] Assignee: Edmond L. dOuville, Evergreen Park, 111.

a part interest [22] Filed: July 18, 1969 [21] Appl. No.: 842,946

[52] U.S. Cl. ..71/29, 71/64 A [51] Int. Cl ..C05c 9/02 [58] Field ofSearch ..71/29, 64 A, 64 F, 64 R [56] References Cited UNITED STATESPATENTS 1,953,419 4/1934 Maclntire ..71/34 X 2,032,608 3/1936 Antrim...7l/64 A X 3,024,098 3/1962 Austin at al ..71/29 Messman 1 Mar. 7,1972 [54] SLOW-RELEASE FERTILIZER SPIKE 3,057,713 10/1962 Gessler..71/64 A HAVING HIGH CRUSH-RESIST E 3,062,637 11/1962 Marples et a1.......71/64 G x 3,502,458 .3/1970 Schenk ..71/64 OTHER PUBLICATIONSl-lackh s Chemical Dictionary, Third Edition, page 78, published byMcGraw- Hill Co., Inc., New York, 1944.

Primary Examiner-Reuben Friedman Assistant ExaminerBennett H. LevensonAttorney-Philip Hill [57] ABSTRACT A slow-release fertilizercomposition, having a crushing strength in excess of 2,000 p.s.i.,comprises a water-soluble urea-formaldehyde resin, a granular fillermaterial and a binder derived from magnesia and phosphoric acid. Thecomposition is prepared as a paste and extruded in the form of a beveledspike.

4 Claims, 4 Drawing Figures PATENTEDMAR 71972 3,647, 416

Fig. 2

I20 1' i "L 1 IN VE N T 0R. Henry 6. Messman ATTORNEY Fig. 1

SLOW-RELEASE FERTILIZER SPIKE HAVING HIGH CRUSH-RESISTANCE BACKGROUND OFTHE INVENTION This invention relates to compositions suitable forcrush-resistant, shaped solids useful as slow-release fertilizers foromamental trees and shrubs, to the configuration of the shaped solidsand to their method of formation.

To stimulate the growth of ornamental trees and shrubs and the like, itis desirable to apply a slow-release fertilizer without materiallydisturbing or disfiguring the surrounding sod or lawn, or burning thelawn by overfertilization. It is conventional to make small-dimaetercore holes in the sod or soil surrounding the trees or shrubs and fillthe holes with powdered fertilizer or liquid fertilizer concentrates.This procedure, while effective, is cumbersome and inconvenient andrequires special equipment.

An alternate solution to this problem is disclosed by A. E. Gessler inU.S. Pat. No. 3,057,713 whereby nutrients are made available to rootsystems by insertion of fertilizer sticks into the soil. These sticksare molded in pointed shapes having a hardened exterior suitable forhammering into the ground when fitted with a protective cap.

There remain the problems of providing both inexpensive, slow-release,uniform combinations of fertilizer nutrients and a simple, convenientmethod of preparing the combinations in a readily usable form.

SUMMARY OF THE INVENTION This invention is a novel crush-resistantcomposition of fertilizer nutrients together with filler and bindermaterials, fashioned in the form of a tapered spike, preferably by anextrusion process.

It is the object of this invention to provide crush-resistant, shapedsolids of a slow-release fertilizer which can be force or driven intothe soil or lawn at spaced points without materially disturbing ordisfiguring the surface. By crush-resistant is meant solid compositionshaving a crushing strength of at least about 2,000 p.s.i. when measuredby ASTM method C-39-66.

Various geometric shapes such as beveled rods, cylinder, prisms,spheroids, and pyramids having a crushing strength in excess of 2,000p.s.i. can be formed or driven into most sods directly, without the useof protective caps and without the necessity of coring the sod or soil.I have discovered a novel composition which is a balanced slow-releasefertilizer and, when properly cast or extruded and air-cured, has therequired high crushing strength. The crushing strength of my compositionis comparable to concrete, exceeding 2,000 p.s.i. and often attaining acrushing strength in excess of 2,500 to 3,000 p.s.i.

My novel crush-resistant slow-release fertilizer composition comprises awater-soluble urea-formaldehyde resin, a granular filler material and abinder cement derived from the reaction of magnesia with a substantiallystoichiometrie quantity of aqueous phosphoric acid. To this compositionmay be added potassium compounds and minor quantities of fertilizertraceelement compounds to provide balanced plant nutrition.

DETAILED DESCRIPTION OF THE INVENTION The essential components of thisnovel composition are a urea-formaldehyde resin, a granular filler and abinder cement.

The urea-formaldehyde (ureaform) resin must be capable of slowlyreleasing nitrogen to he soil in an available form by dissolution inwater. Accordingly the choice of resin is limited to the water-solubleurea-formaldehyde resins. These watersoluble resins have high nitrogencontents, generally in the range from 35 to 40 weight percent. Aparticularly suitable ureaform material, sold by Du Pont under the tradename U- ramite," contains 38 percent nitrogen. This ureaform has ameasurable but low water solubility. in addition to providing nitrogenvalues it acts as a binder and as a controlled waterproofing agent.

The filler material should be ground and/or screened to provide auniform mass of 16- to 20-mesh granules. Suitable granular fillermaterials include petroleum coke, sand, clays, expanded clays, and cokebreeze derived from coal. A unique and desirable component is finelydivided petroleum coke. Socalled fluid coke" from a conventional fluidcoker may be directly employed. Coke breeze may also be employed withoutfurther treatment. Petroleum is an igneous material and petroleum cokeis a thermal residue of petroleum, rich in vanadium and nickel as wellas other trace metals present in vegetable matter. It also contains bothfree and combined sulfur. The coke serves as an aggregate or filler andhas the advantage of low density when compared to sand or clays. Cokefrom a delayed coker, calcined and ground and/or screened to 16- to20-mesh size, is likewise suitable and can be employed.

The binder cement is derived from the reaction of magnesia with aqueousphosphoric acid. Magnesia is readily obtained as calcined magnesite. Thephosphoric acid is preferably about 50 percent aqueous H PO The amountintroduced should be sufficient to react with the magnesite to form amagnesium phosphate binder or cement. The composition of the binder isbelieved to be Newberyite cement corresponding to MgHPO, 3H O or a formof magnesium oxyphosphate, for example MgOMgl-l. (PO It is not essentialthat the magnesium oxide and phosphoric acid be in the exactstoichiometric ratio. Either the phosphoric acid or magnesium oxide maybe present in moderate excess. Part of the phosphate required i may besupplied by the addition of salts such as diammonium phosphate. Properselection of the proportions of these binder components is a majorfactor in achieving the extraordinary crushing strengths of these novelcompositions.

Other components may be included in this novel composition to achievedesirable balances of fertilizer nutrients. Potassium is a majorfertilizer nutrient and is preferably introduced as a salt; for example,potassium chloride. Fertilizer trace elements may be added in the formof salts (e.g., chloride or sulfate) of metals such as boron, iron,manganese, molybdenum, nickel, vanadium and zinc, a desirable rangebeing about 0.1 to 2.0 weight percent.

Proportions of components of this novel composition, suitable to provideboth slow-release fertilization and high crushresistance, may beselected from within the following ranges, expressed as parts by weight:

30 to 50 parts urea-formaldehyde resin,

10 to 30 parts granular filler,

10 to 30 parts binder cement,

0 to 10 parts potassium salt, calculated as potassium oxide,

and

0 to 2 parts fertilizer trace elements.

The novel compositions of my invention can be fashioned into a taperedspike, for forcing into the soil, by any technique known to one skilledin the art. Prior art production methods for such shaped solidsgenerally suggest the mixing together of the components to obtain amoldable paste or dough, forming the spikes in molds, and finally dryingand finishing, the latter operation being conducted at elevatedtemperatures.

The formation of the shaped solids by extrusion is preferred to moldingbecause it is more economical and lends itself better to massproduction, Although pointed shaped cannot be made by extrusiontechnique employing a vertical cutoff, beveled shapes can be so made (byextrusion with vertical cutoff) and these shapes are as easily forcedinto the soil as the pointed shapes. With high crushing strength theycan be forced into the soil without fracture.

Although pointed elongated shapes such as those proposed in U.S. Pat.No. 3,057,713 can be forced into soft soils when protected by a rubbercap, I prefer shaped solids which can be formed by extrusion andperpendicular cutting and which have a high crushing strength. Suchshaped solids are particularly exemplified by the embodiments shown inthe attached drawing. FIG. I is a perspective drawing of the preferredembodiment of the fertilizer spike. FIGS. 2, 3 and 4 are perspectivedrawings of other suitable embodiments.

Referring particularly to FIG. 1, a preferred shape consists of arectangular or square top 12, a planar face 11 extending the fulllength, of the spike 10, an upper face 13 depending from top 12 andnormal to face 1 l and a lower'face 14 extending from the bottom edge of13 to the extremity of the spike as described by 11. The obverse facescorresponding to 11, 13 and 14 are not shown. Among other suitableshapes of the spike are those providing a convex lower face such as 14ain FIG. 2 or a concave lower face such as 14c in FIG. 4 and, optionally,a flared upper face such as 13b in FIG. 3. In general the lengthdescribed by 11 should be between 4 and 10 inches, preferably between 5and 8 inches, and the cross-sectional area at the top end 12 should bebetween I and 3 square inches. The total exposed surface on the slantedor beveled face 14 and its obverse face, i.e., the combined surfaceareas of these faces, should be at least 4 times the rectangular sur'face on the flat or top end 12. In order to form these shapes byextrusion and perpendicular cutting, a die whose opening has a contouredge configuration typically illustrated by the facesv ll, 11a, 11b andllc is used. These shapes, when formed from compositions with ASTMcrushing strengths above 2,000 p.s.i., require no protective caps forgeneral use.

EXAMPLE The following example is illustrative, without limitation, ofthe technique employed in fashioning my novel composition into acrush-resistant tapered spike.

The following ingredients were brought together employing the weightproportions shown.

45 parts Cnlcincd Magnesitc (60% Mg) I I parts 75% Phtisphoric Acid r(54% P,(), i I 405 parts Ureaform (Du lont Uramite) (38% N) 2 K punsDiammonium Phosphate (21% N-53% P 0 I30 parts Potassium Chloride (62% K0) 5 parts Ferric Oxide 20 parts Fertilizer Trace Elements 1' (TennesseeCorp.) 200 parts Fluid Coker Petroleum Coke (lo-20 mesh) [000 parts Allthe ingredients except the :petroleum coke and phosphoric acid were drymixed. The dry mixture was then thoroughly mixed with the' phosphoricacid which had been diluted to a strength of about 50 percent. To thispasty mixture was then added the petroleum coke to provide a thickextrudable mix or flux.

The compaction from the volume of the original loose dry mix was about 3to l and from the lightly tamped mix about 2 to l. The thick pastemixture did not stick to the surfaces of molding or extrusion equipment.

The green strength of the freshly-formed shapes from this formulationwas ample for handling and the shapes cured at room temperatures to astrength of about 2,400 p.s.i. in 10 days. 1

In a preferred method of operation the thick paste mixture of the aboveexample is extruded through a die whose contour edge describes the shapeillustrated by face 11 in FIG. 1. The overall length is 7 inches and themaximum width is 1 inch along the upper 4 inches of the shape. The lower3 inches of the shape are tapered uniformly to describe a tapered spike.As the paste is extruded from the die it is cut into l-inch thick stripsto provide the 3-dimensional shaped spike illustrated in FIG. 1, thusdetermining the cross-sectional area of the spike, apart from thebeveled end portion thereof, wherein the combined areas of the slantedor beveled surfaces (face 14 and its obverse) are greater than 6 squareinches and the top cross section rectangular area (face 12) is 1 squareinch, with the beveled end portion of the spike manifesting adiminishing cross-sectional area.

The calculated analysis for the ingredients of this example lSl7N-l0P-K. Trace elements are present in the following amounts:

One skilled in the art can adjust the specific composition of thisexample to provide shapes suitable for various soil conditions, provided30 to 50 percent by weight water-soluble urea formaldehyde resin and atleast 10 percent by weight of each of the filler and the binder cementare present in the hardened product.

I claim: 7

l. A slow-release fertilizer composition, shaped as a spike having abeveled end portion and having a crushing strength of at least2,000p.s.i., comprising I a. 30-50 weight percent water-solubleureaformaldehyde resin containing about 35 to 40 weight percentnitrogen;

b. 5-10 weight percent potassium salts, calculated as potassium oxide;

c. l030 weight percent ground coke; and

d. 10-30 weight percent of binder cement, derived from the substantiallystoichiometric reaction of magnesia with aqueous 50 percent phosphoricacid;

the top end of the spike, opposite the beveled portion thereof, having across-sectional area between about I and 3 square inches, saidcross-sectional area diminishing along the beveled portion of the spike,the combined areas of the obverse beveled surfaces being at least 4times the surface area at the said top end of the spike.

2. The composition of claim I, additionally comprising about 0.1 to 2.0weight percent fertilizer trace elements.

3. A method for the manufacture of homogeneous, crushresistant,slow-release fertilizer compositions, shaped in the form of a spikehaving a beveled end portion and having a crushing strength of at least2,000 p.s.i., comprising the steps of:

a. preparing a dry powder mixture comprising, in parts by weight, about45 parts magnesia, and about 405 parts of a urea-formaldehyde resincontaining about 35 to 40 weight percent nitrogen;

bl converting the dry powder mixture to a uniform paste by agitating thepowder mixture with about 1 10 parts of percent phosphoric acid dilutedwith sufficient water to reduce the acid strength to about 50 percent;

c. blending into the paste about 200 parts ground coke;

d. extruding the blended paste through a die having an opening whosecounter edge configuration is shaped to define the length of a spikehaving a beveled end portion, said length being within the range from 5to 8 inches, the cross-sectional area of the said spike extrudate alongthe said beveled end portion diminishing to determine the same;

cutting the shaped spike extrudate of d into strips to define the crosssectional area of the beveled spike at its top end and above the beveledportion thereof, said cross sectional area being at least I square inchbut no greater than required to provide a top cross-sectional area ofthe spike of about 3 square inches, the combined surface areas of theobverse beveled faces of the spike being at least 4 times the surfacearea of the top end; and

f. drying the extruded spike at ambient temperature for about 10 days,to provide a cured fertilizer composition comprising a spike having abeveled end portion.

4. The method of claim 3 wherein the dry powder mixture additionallycomprises about I30 parts of potassium chloride.

i i I i

2. The composition of claim 1, additionally comprising about 0.1 to 2.0weight percent fertilizer trace elements.
 3. A method for themanufacture of homogeneous, crush-resistant, slow-release fertilizercompositions, shaped in the form of a spike having a beveled end portionand having a crushing strength of at least 2,000 p.s.i., comprising thesteps of: a. preparing a dry powder mixture comprising, in parts byweight, about 45 parts magnesia, and about 405 parts of aurea-formaldehyde resin containing about 35 to 40 weight percentnitrogen; b. converting the dry powder mixture to a uniform paste byagitating the powder mixture with about 110 parts of 75 percentphosphoric acid diluted with sufficient water to reduce the acidstrength to about 50 percent; c. blending into the paste about 200 partsground coke; d. extruding the blended paste through a die having anopening whose counter edge configuration is shaped to define the lengthof a spike having a beveled end portion, said length being within therange from 5 to 8 inches, the cross-sectional area of the said spikeextrudate along the said beveled end portion diminishing to determinethe same; e. cutting the shaped spike extrudate of d into strips todefine the cross sectional area of the beveled spike at its top end andabove the beveled portion thereof, said cross sectional area being atleast 1 square inch but no greater than required to provide a topcross-sectional area of the spike of about 3 square inches, the combinedsurface areas of the obverse beveled faces of the spike being at least 4times the surface area of the top end; and f. drying the extruded spikeat ambient temperature for about 10 days, to provide a cured fertilizercomposition comprising a spike having a beveled end portion.
 4. Themethod of claim 3 wherein the dry powder mixture additionally comprisesabout 130 parts of potassium chloride.